First unit, second unit and method

ABSTRACT

In order to make it possible to report an amount of data from a secondary node (SN) to a master node (MN) in dual connectivity, there is provided a first unit according to the present disclosure which is a first unit of a central unit of a first base station. The first unit includes a controller and a transceiver. The central unit is configured to host at least PDCP layer in the first base station; and is connected to a distributed unit via a first interface, the distributed unit hosting RLC, MAC and PHY layers in the first base station. The controller is configured to host at least a user plane of the PDCP layer hosted by the central unit; and the transceiver is configured to transmit, to a second unit via a second interface, first information indicative of a volume of data processed by the first unit. The second unit is configured to host at least a control plane of the PDCP layer hosted by the central unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/270,161, filed on Feb. 7, 2019, which claims priority from JapanesePatent Application No. 2018-023331, filed on Feb. 13, 2018, thedisclosures of which are incorporated herein by reference in theirentirety.

BACKGROUND Technical Field

The present disclosure relates to a first unit, a second unit and amethod.

Background Art

In Third-Generation Partnership Project (3GPP) Release 15, E-UTRA-NRDual Connectivity (EN-DC) has been specified (see NPL 1). According toEN-DC, a user equipment (UE) is connected to one evolved Node B (eNB)operating as a master node (MN) and an en-gNB operating as a secondarynode (SN).

Further, Secondary RAT Data Usage Report function has been specified asa function of the EN-DC (see NPL 2). The en-gNB counts (measures) anamount of user data transported between the en-gNB and a UE using NewRadio (NR) that is a secondary radio access technology (RAT) and reportsthe amount of data (data volume) to an MeNB (eNB which is an MN) with anX2AP:Secondary RAT Data Usage Report message.

-   [NPL 1] 3GPP TS 37.340 V15.0.0 (2017-12), “3rd Generation    Partnership Project; Technical Specification Group Radio Access    Network; Evolved Universal Terrestrial Radio Access (E-UTRA) and NR;    Multi-connectivity; Stage 2 (Release 15)”-   [NPL 2] 3GPP TS 36.423 V15.0.0 (2017-12), “3rd Generation    Partnership Project; Technical Specification Group Radio Access    Network; Evolved Universal Terrestrial Radio Access    Network(E-UTRAN); X2 application protocol (X2AP) (Release 15)”

SUMMARY

However, how to realize the Secondary RAT Data Usage Report function hasnot been specified. More specifically, no method for an en-gNB that isan SN to obtain the amount of data has been specified.

An example object of the present disclosure is to provide a mechanismwhich makes it possible to report the amount of data from a secondarynode (SN) to a master node (MN) in dual connectivity.

According to an example aspect of the present disclosure, there isprovided a first unit of a central unit of a first base station. Thefirst unit includes a controller and a transceiver. The central unit isconfigured to host at least PDCP layer in the first base station; and isconnected to a distributed unit via a first interface, the distributedunit hosting RLC, MAC and PHY layers in the first base station. Thecontroller is configured to host at least a user plane of the PDCP layerhosted by the central unit; and the transceiver is configured totransmit, to a second unit via a second interface, first informationindicative of a volume of data processed by the first unit. The secondunit is configured to host at least a control plane of the PDCP layerhosted by the central unit.

According to an example aspect of the present disclosure, there isprovided a second unit of a central unit of a first base station. Thesecond unit includes a controller and a transceiver. The central unit isconfigured to host at least PDCP layer in the first base station; and isconnected to a distributed unit via a first interface, the distributedunit hosting RLC, MAC and PHY layers in the first base station. Thecontroller is configured to host at least a control plane of the PDCPlayer hosted by the central unit; and the transceiver is configured toreceive, from a first unit via a second interface, first informationindicative of a volume of data processed by the first unit. The firstunit is configured to host at least a user plane of the PDCP layerhosted by the central unit.

According to an example aspect of the present disclosure, there isprovided a method performed by a first unit of a central unit of a firstbase station. At least PDCP layer in the first base station is hosted bythe central unit; and the central unit is connected to a distributedunit via a first interface, the distributed unit hosting RLC, MAC andPHY layers in the first base station. The method includes hosting atleast a user plane of the PDCP layer hosted by the central unit; andtransmitting to a second unit via a second interface, first informationindicative of a volume of data processed by the first unit. The secondunit is configured to host at least a control plane of the PDCP layerhosted by the central unit.

In an example aspect of the present disclosure, there may be provided amethod including a process step to operate the above-described functionsof the first unit, the second unit or the communication apparatus. In anexample aspect of the present disclosure, there may be provided aprogram causing a processor to perform the method or a computer-readablenon-transitory recording medium having stored thereon the program.

According to an example aspect of the present disclosure, it will bepossible to report the amount of data from a secondary node (SN) to amaster node (MN) in dual connectivity. Note that an example aspect ofthe present disclosure may exert other advantageous effects instead ofthe above advantageous effect or together with the above advantageouseffect.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory diagram illustrating an example of a schematicconfiguration of a system according to example embodiments;

FIG. 2 is an explanatory diagram for describing an example of layeredprocessing of respective radio bearers according to the exampleembodiments;

FIG. 3 is an explanatory diagram for describing an example of splittinga first base station according to the example embodiments;

FIG. 4 is an explanatory diagram for describing an example of splittingthe first base station according to a first example embodiment;

FIG. 5 is an explanatory diagram for describing an example of data routefor an MN Terminated bearer according to the first example embodiment;

FIG. 6 is a block diagram illustrating an example of a schematicconfiguration of a CU according to the first example embodiment;

FIG. 7 is a block diagram illustrating an example of a schematicconfiguration of a DU according to the first example embodiment;

FIG. 8 is a block diagram illustrating an example of a schematicconfiguration of a second base station according to the first exampleembodiment;

FIG. 9 is a block diagram illustrating an example of a schematicconfiguration of a terminal apparatus according to the first exampleembodiment;

FIG. 10 is the first explanatory diagram for describing an example of aDATA USAGE REPORT message according to the first example embodiment;

FIG. 11 is the second explanatory diagram for describing an example ofthe DATA USAGE REPORT message according to the first example embodiment;

FIG. 12 is the third explanatory diagram for describing an example ofthe DATA USAGE REPORT message according to the first example embodiment;

FIG. 13 is an explanatory diagram for describing an example of a UECONTEXT SETUP REQUEST message according to the first example embodiment;

FIG. 14 is an explanatory diagram for describing an example of a UECONTEXT MODIFICATION REQUEST message according to the first exampleembodiment;

FIG. 15 is a first explanatory diagram for describing an example of aSECONDARY RAT DATA USAGE REPORT message according to the first exampleembodiment;

FIG. 16 is a second explanatory diagram for describing an example of aSECONDARY RAT DATA USAGE REPORT message according to the first exampleembodiment;

FIG. 17 is a sequence diagram for describing an example of a schematicflow of a process according to the first example embodiment;

FIG. 18 is an explanatory diagram for describing an example of a DL DATADELIVERY STATUS frame according to an example alteration of the firstexample embodiment;

FIG. 19 is a sequence diagram for describing an example of a schematicflow of a process according to the example alteration of the firstexample embodiment;

FIG. 20 is an explanatory diagram for describing an example of splittinga first base station according to a second example embodiment;

FIG. 21 is a block diagram illustrating an example of a schematicconfiguration of a CU according to the second example embodiment;

FIG. 22 is a block diagram illustrating an example of a schematicconfiguration of a DU according to the second example embodiment;

FIG. 23 is a sequence diagram for describing an example of a schematicflow of a process according to the second example embodiment;

FIG. 24 is a sequence diagram for describing an example of a schematicflow of a process according to the example alteration of the secondexample embodiment;

FIG. 25 is an explanatory diagram for describing an example of splittinga first base station according to a third example embodiment;

FIG. 26 is an explanatory diagram for describing an example of splittinga first base station (higher layer split) according to a third exampleembodiment;

FIG. 27 is a block diagram illustrating an example of a schematicconfiguration of a CU-CP according to the third example embodiment;

FIG. 28 is a block diagram illustrating an example of a schematicconfiguration of a CU-UP according to the third example embodiment;

FIG. 29 is a sequence diagram for describing a first example of aschematic flow of a process according to the third example embodiment;

FIG. 30 is a sequence diagram for describing a second example of aschematic flow of a process according to the third example embodiment;

FIG. 31 is a sequence diagram for describing a third example of aschematic flow of a process according to the third example embodiment;

FIG. 32 is a sequence diagram for describing a fourth example of aschematic flow of a process according to the third example embodiment;

FIG. 33 is a block diagram illustrating an example of a schematicconfiguration of a first communication apparatus according to the fourthexample embodiment;

FIG. 34 is a block diagram illustrating an example of a schematicconfiguration of a second communication apparatus according to thefourth example embodiment;

FIG. 35 is a block diagram illustrating an example of a schematicconfiguration of a terminal apparatus according to the fourth exampleembodiment;

DESCRIPTION OF THE EXAMPLE EMBODIMENTS

Example embodiments of the present disclosure (hereinafter, referred toas “the present example embodiments”) will be described in detail belowwith reference to the accompanying drawings. Note that, in the presentSpecification and drawings, elements to which similar descriptions areapplicable are denoted by the same reference signs, whereby overlappingdescriptions may be omitted.

Descriptions will be given in the following order.

1. System Configuration

2. First Example Embodiment

-   -   2.1. Splitting First Base Station    -   2.2. Configuration of Each Node        -   2.2.1. Configuration of Central Unit (CU)        -   2.2.2. Configuration of Distributed Unit (DU)        -   2.2.3. Configuration of Second Base Station        -   2.2.4. Configuration of Terminal Apparatus    -   2.3. Technical Features    -   2.4. Example Alterations

3. Second Example Embodiment

-   -   3.1. Splitting First Base Station    -   3.2. Configuration of Each Node        -   3.2.1. Configuration of Central Unit (CU)        -   3.2.2. Configuration of Distributed Unit (DU)    -   3.3. Technical Features    -   3.4. Example Alterations

4. Third Example Embodiment

-   -   4.1. Splitting First Base Station    -   4.2. Configuration of Each Node        -   4.2.1. Configuration of CU-CP        -   4.2.2. Configuration of CU-UP    -   4.3. Technical Features

5. Fourth Example Embodiment

-   -   5.1. Configuration of Each Node        -   5.1.1. Configuration of First Communication Apparatus        -   5.1.2. Configuration of Second Communication Apparatus        -   5.1.3. Configuration of Terminal Apparatus    -   5.2. Technical Features

1. System Configuration

With reference to FIG. 1, an example configuration of a system 1according to the example embodiments will be described. FIG. 1 is anexplanatory diagram illustrating an example of a schematic configurationof the system 1 according to the example embodiments. Referring to FIG.1, the system 1 includes a core network 10, a first base station 100, asecond base station 400 and a terminal apparatus 500.

(1) Conformance to Standards/Specifications

For example, the system 1 is a system that conforms to 3GPP standards orspecifications. More specifically, for example, the system 1 conforms tofifth generation (5G) or New Radio (NR) standards or specifications. Thesystem 1 may also conform to Long Term Evolution (LTE) or SystemArchitecture Evolution (SAE) standards or specifications. LTE herein mayrefer to LTE-Advanced or enhanced LTE (eLTE), to (normal) LTE or to anyother variant of LTE.

(2) Interface

The first base station 100 communicates with the core network 10 via aninterface 30. The second base station 400 communicates with the corenetwork 10 via an interface 40.

As an example, the core network 10 is an Evolved Packet Core (EPC) (thatis, a core network of fourth-generation (4G)). In this case, forexample, the interface 30 and the interface 40 are S1-interfaces.

As another example, the core network 10 may be fifth-generation corenetwork (5GC). In this case, the interface 30 and the interface 40 maybe NG interfaces.

The first base station 100 and the second base station 400 maycommunicate with each other via an interface 50.

(3) Dual Connectivity

The first base station 100 communicates wirelessly with the terminalapparatus 500. The second base station 400 also communicates wirelesslywith the terminal apparatus 500. The terminal apparatus 500 supportsdual connectivity and, for example, is connected to the first basestation 100 and the second base station 400 at the same time. Amongothers, in the example embodiments, the first base station 100 operates,for the terminal apparatus 500, as a secondary node (SN) of dualconnectivity and the second base station 400 operates, for the terminalapparatus 500, as a master node (MN) of the dual connectivity.

In the example embodiments, the dual connectivity uses at least NewRadio (NR) as a radio access technology (RAT). That is, at least one ofthe master node (the second base station 400) and the secondary node(the first base station 100) uses NR to communicate with the terminalapparatus 500. Note that NR mentioned above is a RAT of 3GPPfifth-generation (5G) and may be referred to as New RAT (NR), 5G NR (NewRadio/RAT) or the like.

NR+LTE

For example, the dual connectivity may be dual connectivity which usesNR and LTE. That is, one of the master node (the second base station400) and the secondary node (the first base station 100) uses NR tocommunicate with the terminal apparatus 500 and the other uses LTE tocommunicate with the terminal apparatus 500. As mentioned above, LTEherein may refer to LTE-Advanced or enhanced LTE (eLTE), to (normal) LTEor to any other variant of LTE.

EN-DC

As an example, the dual connectivity is EN-DC, the first base station100 is an en-gNB and the second base station 400 is a master eNB (MeNB).That is, the second base station 400 (MeNB) being the master node (MN)uses LTE as a RAT to communicate with the terminal apparatus 500 and thefirst base station 100 (en-gNB) being the secondary node (SN) uses NR asa RAT to communicate with the terminal apparatus 500. In this case, thecore network 10 is the EPC and the interface 50 between the first basestation 100 and the second base station 400 is an X2 interface.

FIG. 2 is an explanatory diagram for describing an example of layeredprocessing of respective radio bearers according to the exampleembodiments. Referring to FIG. 2, the first base station 100 (en-gNB)being the secondary node (SN), the second base station 400 (MeNB) beingthe master node (MN) and respective radio bearers are shown. There areradio bearers including MN Terminated bearers that are terminated at theMN (that is, PDCP thereof are located at the MN) and SN Terminatedbearers that are terminated at the SN (that is, PDCP thereof are locatedat the SN). Further, the MN Terminated bearers includes a Master CellGroup (MCG) bearer, a Secondary Cell Group (SCG) bearer and a splitbearer. Similarly, the SN Terminated bearers includes an MCG bearer, anSCG bearer and a split bearer. The MCG bearers are radio bearers havingRLC bearers in MCG and processing of RLC layer, MAC layer and physicallayer for the MCG bearers are performed at the MN (the second basestation 400). The SCG bearers are radio bearers having RLC bearers inSCG and processing of RLC layer, MAC layer and physical layer for theSCG bearers are performed at the SN (the first base station 100). Splitbearers are radio bearers having RLC bearers both in MCG and SCG andprocessing of RLC layer, MAC layer and physical layer for the Splitbearers are performed both at the MN (the second base station 400) andthe SN (the first base station 100).

Note that, though an example where the dual connectivity is the EN-DChas been described, the example embodiments are not limited to thatexample.

NGEN-DC

As an example, the dual connectivity may be NG-RAN E-UTRA-NR DualConnectivity (NGEN-DC), the first base station 100 may be a gNBoperating as an SN and the second base station 400 may be an ng-eNBoperating as an MN. In this case, the core network 10 may be a 5GC andthe interface 50 between the first base station 100 and the second basestation 400 may be an Xn interface.

NE-DC

As another example, the dual connectivity may be NR-E-UTRA DualConnectivity (NE-DC), the first base station 100 may be a ng-eNBoperating as an SN and the second base station 400 may be a gNBoperating as an MN. In this case, the core network 10 may be a 5GC andthe interface 50 between the first base station 100 and the second basestation 400 may be an Xn interface.

NR Only

Alternatively, the dual connectivity may be dual connectivity that usesNR (without using LTE). That is, both of the master node (the secondbase station 400) and the secondary node (the first base station 100)may use NR to communicate with the terminal apparatus 500. The firstbase station 100 may be a gNB operating as an SN and the second basestation 400 may be a gNB operating as an MN. In this case, the corenetwork 10 may be a 5GC and the interface 50 between the first basestation 100 and the second base station 400 may be an Xn interface.

Note that the first base station 100 may be a base station of a firstoperator and the second base station 400 may be a base station of asecond operator that is different from the first operator. That is, thedual connectivity may be dual connectivity between operators.

(4) Splitting of First Base Station

For example, the first base station 100 may include a central unit (CU)and one or more distributed units (DUs).

FIG. 3 is an explanatory diagram for describing an example of splittingthe first base station 100 according to an example embodiment. Referringto FIG. 3, the central unit (CU) 200 and the distributed units (DUs) 300included in the first base station 100 are shown. The CU 200 and each DU300 communicate with each other via the interfaces 60. Two DUs 300 areshown in this example, however, the first base station 100 may includethree or more DUs 300 or include only one DU 300.

For example, a base station may be split by Higher Layer Split or LowerLayer Split. The following first example embodiment will be an exampleembodiment of the Higher Layer Split and the following second exampleembodiment will be an example embodiment of the Lower Layer Split.

Further, the central unit (CU) 200 may include a first central unit fora control plane and a second central unit for a user plane. The firstcentral unit may be referred to as CU-CP and the second central unit maybe referred to as CU-UP. The following third example embodiment will bean example embodiment especially focusing on the case of such splittingof the CU 200.

Alternatively, the CU 200 may be a first central unit (CU-CP) for acontrol plane or a second central unit (CU-UP) for a user plane.

2. First Example Embodiment

Next, the first example embodiment of the present invention will bedescribed with reference to FIGS. 4 to 19.

<<2.1. Splitting First Base Station>>

First, splitting the first base station 100 according to the firstexample embodiment will be described with reference to FIGS. 4 and 5.

In the first example embodiment, the first base station 100 includes acentral unit 200 and distributed units that perform processing of RLCand MAC layers. That is, in the first example embodiment, the first basestation 100 is split by the Higher Layer Split.

FIG. 4 is an explanatory diagram for describing an example of splittingthe first base station 100 according to the first example embodiment.Referring to FIG. 4, the CU 200 and the DU 300 included in the firstbase station 100 are shown. The PDCP layer is located at the CU 200 andthe RLC, MAC and physical (PHY) layers are located at the DU 300. Thatis, the CU 200 performs processing of the PDCP layer and the DU 300performs processing of the RLC, MAC and PHY layers. In this case, theinterface 60 is an F1 interface.

An example where the PDCP layer is located at the CU 200 has beendescribed with reference to FIG. 4, however, Service Data AdaptationProtocol (SDAP) layer may be located at the CU 200, especially, in thecase of NGEN-DC or NE-DC.

In such a case of Higher Layer Split, data transported between the SN(the first base station 100) and the terminal apparatus 500 through anMN Terminated bearer may be transported between the MN (the second basestation 400) and the DU 300 of the SN by passing through the CU 200 ofthe SN (first example). Alternatively, such data may be transportedbetween the MN (the second base station 400) and the DU 300 of the SNdirectly without passing through the CU 200 of the SN (second example).

FIG. 5 is an explanatory diagram for describing an example of data routefor an MN Terminated bearer according to the first example embodiment.Referring to FIG. 5, the CU 200 and the DU 300 included in the firstbase station 100 are shown along with the second base station 400. As afirst example, the data transported between the SN (the first basestation 100) and the terminal apparatus 500 through an MN Terminatedbearer may be transported between the MN (the second base station 400)and the DU 300 of the SN by passing through the CU 200. That is, thedata may be transported via the interface 50 (for example, X2-U) and theinterface 60 (for example, F1-U) along the route 70. As a secondexample, the data may be transported between the MN (the second basestation 400) and the DU 300 of the SN directly without passing throughthe CU 200. That is, the data may be transported along the route 80.

Note that, though an example of splitting the first base station 100 hasbeen described, the second base station 400 may be split similarly tothe first base station 100. Alternatively, a different splitting (forexample, Lower Layer Split) than that for the first base station 100(Higher Layer Split) may be applied to the second base station 400.

In the first example embodiment, for example, the CU 200 is a centralunit both for the control plane (CP) and the user plane (UP). In thiscase, the CU 200 may be a single unit. Alternatively, the CU 200 mayinclude a CU-CP which is a first central unit for the control plane anda CU-UP which is a second central unit for the user plane.

Alternatively, in the first example embodiment, the CU 200 may be theCU-CP which is the first central unit for the control plane. In thiscase, the first base station 100 may include the CU-UP which is thesecond central unit for the user plane separately from the CU-UP (CU200).

<<2.2. Configuration of Each Node>>

Next, a configuration of each node will be described with reference toFIGS. 6 to 9.

<2.2.1. Configuration of Central Unit (CU)>

FIG. 6 is a block diagram illustrating an example of a schematicconfiguration of the CU 200 according to the first example embodiment.Referring to FIG. 6, the CU 200 includes a first network communicationsection 210, a second network communication section 220, a storagesection 230 and a processing section 240.

(1) First Network Communication Section 210

The first network communication section 210 receives a signal from theDU 300 and transmits a signal to the DU 300.

(2) Second Network Communication Section 220

The second network communication section 220 receives a signal from thesecond base station 400 and transmits a signal to the second basestation 400.

The second network communication section 220 may receive a signal fromthe core network 10 and transmit a signal to the core network 10.

(3) Storage Section 230

The storage section 230 stores a program (instructions) and parametersfor operation of the CU 200 as well as various data temporarily orpermanently. The program includes one or more instructions for operationof the CU 200.

(4) Processing Section 240

The processing section 240 provides various functions of the CU 200. Theprocessing section 240 includes a first communication processing section241 and a second communication processing section 243. Note that theprocessing section 240 may further include another constituent elementthan these constituent elements. That is, the processing section 240 mayperform operations other than the operations of these constituentelements.

For example, the processing section 240 (the first communicationprocessing section 241) communicates with the DU 300 via the firstnetwork communication section 210. For example, the processing section240 (the second communication processing section 243) communicates withthe second base station 400 (or the core network 10) via the secondnetwork communication section 220.

(5) Implementation Examples

Each of the first network communication section 210 and the secondnetwork communication section 220 may be implemented with a networkadapter, a network interface card and/or the like. The storage section230 may be implemented with a memory (for example, a non-volatile memoryand/or a volatile memory), hard disc and/or the like. The processingsection 240 may be implemented with one or more processors such as BaseBand (BB) processors, another type of processors and/or the like. Thefirst communication processing section 241 and the second communicationprocessing section 243 may be implemented with the same processor orwith respective different processors. The above memory (the storagesection 230) may be included in the one or more processors or may beexternal to the one or more processors.

The CU 200 may include a memory that stores programs (instructions) andone or more processors that are capable of executing the programs(instructions). The one or more processors may execute the programs toperform operations of the processing section 240 (operations of thefirst communication processing section 241 and/or the secondcommunication processing section 243). The programs may be programs forcausing a processor to execute the operations of the processing section240 (operations of the first communication processing section 241 and/orthe second communication processing section 243).

Note that the CU 200 may be virtualized. That is, the CU 200 may beimplemented as a virtual machine. In this case, the CU 200 (virtualmachine) may operate as a virtual machine on a physical machine(hardware) including a processor, memory and the like and on ahypervisor.

<2.2.2. Configuration of Distributed Unit (DU)>

FIG. 7 is a block diagram illustrating an example of a schematicconfiguration of the DU 300 according to the first example embodiment.Referring to FIG. 7, the DU 300 includes a wireless communicationsection 310, a network communication section 320, a storage section 330and a processing section 340.

(1) Wireless Communication Section 310

The wireless communication section 310 wirelessly transmits and receivessignals. For example, the wireless communication section 310 receives asignal from the terminal apparatus 500 and transmits a signal to theterminal apparatus 500.

(2) Network Communication Section 320

The network communication section 320 receives a signal from the CU 200and transmits a signal to the CU 200. The network communication section320 may receive a signal from another node (for example, the second basestation 400) and transmit a signal such another node.

(3) Storage Section 330

The storage section 330 stores a program (instructions) and parametersfor operation of the DU 300 as well as various data temporarily orpermanently. The program includes one or more instructions for operationof the DU 300.

(4) Processing Section 340

The processing section 340 provides various functions of the DU 300. Theprocessing section 340 includes a first communication processing section341, a second communication processing section 343 and a count section345. The count section 345 may also be referred to as measurementsection 345. Note that the processing section 340 may further includeanother constituent element than these constituent elements. That is,the processing section 340 may perform operations other than theoperations of these constituent elements.

For example, the processing section 340 (the first communicationprocessing section 341) communicates with the terminal apparatus 500 viathe wireless communication section 310. For example, the processingsection 340 (the second communication processing section 343)communicates with the CU 200 (or the second base station 400) via thenetwork communication section 320.

(5) Implementation Examples

The wireless communication section 310 may be implemented with anantenna, a high frequency (Radio Frequency (RF)) circuit and the likeand the antenna may be a directional antenna. The network communicationsection 320 may be implemented with a network adapter, a networkinterface card and/or the like. The storage section 330 may beimplemented with a memory (for example, a non-volatile memory and/or avolatile memory), hard disc and/or the like. The processing section 340may be implemented with one or more processors such as Base Band (BB)processors, another type of processors and/or the like. The firstcommunication processing section 341, the second communicationprocessing section 343 and the count section 345 may be implemented withthe same processor or with respective different processors. The abovememory (the storage section 330) may be included in the one or moreprocessors or may be external to the one or more processors.

The DU 300 may include a memory that stores programs (instructions) andone or more processors that are capable of executing the programs(instructions). The one or more processors may execute the programs toperform operations of the processing section 340 (operations of thefirst communication processing section 341, the second communicationprocessing section 343 and/or the count section 345). The programs maybe programs for causing a processor to execute the operations of theprocessing section 340 (operations of the first communication processingsection 341, the second communication processing section 343 and/or thecount section 345).

Note that the DU 300 may be virtualized. That is, the DU 300 may beimplemented as a virtual machine. In this case, the DU 300 (virtualmachine) may operate as a virtual machine on a physical machine(hardware) including a processor, memory and the like and on ahypervisor.

<2.2.3. Configuration of Second Base Station>

FIG. 8 is a block diagram illustrating an example of a schematicconfiguration of the second base station 400 according to the firstexample embodiment. Referring to FIG. 8, the second base station 400includes a wireless communication section 410, a network communicationsection 420, a storage section 430 and a processing section 440.

(1) Wireless Communication Section 410

The wireless communication section 410 wirelessly transmits and receivessignals. For example, the wireless communication section 410 receives asignal from the terminal apparatus 500 and transmits a signal to theterminal apparatus 500.

(2) Network Communication Section 420

The network communication section 420 receives a signal from the firstbase station 100 or the core network 10 and transmits a signal to thefirst base station 100 or the core network 10.

(3) Storage Section 430

The storage section 430 stores a program (instructions) and parametersfor operation of the second base station 400 as well as various datatemporarily or permanently. The program includes one or moreinstructions for operation of the second base station 400.

(4) Processing Section 440

The processing section 440 provides various functions of the second basestation 400. The processing section 440 includes a first communicationprocessing section 441 and a second communication processing section443. Note that the processing section 440 may further include anotherconstituent element than these constituent elements. That is, theprocessing section 440 may perform operations other than the operationsof these constituent elements.

For example, the processing section 440 (the first communicationprocessing section 441) communicates with the terminal apparatus 500 viathe wireless communication section 410. For example, the processingsection 440 (the second communication processing section 443)communicates with the first base station 100 or the core network 10 viathe network communication section 420.

(5) Implementation Examples

The wireless communication section 410 may be implemented with anantenna, a high frequency (RF) circuit and the like and the antenna maybe a directional antenna. The network communication section 420 may beimplemented with a network adapter, a network interface card and/or thelike. The storage section 430 may be implemented with a memory (forexample, a non-volatile memory and/or a volatile memory), hard discand/or the like. The processing section 440 may be implemented with oneor more processors such as Base Band (BB) processors, another type ofprocessors and/or the like. The first communication processing section441 and the second communication processing section 443 may beimplemented with the same processor or with respective differentprocessors. The above memory (the storage section 430) may be includedin the one or more processors or may be external to the one or moreprocessors.

The second base station 400 may include a memory that stores programs(instructions) and one or more processors that are capable of executingthe programs (instructions). The one or more processors may execute theprograms to perform operations of the processing section 440 (operationsof the first communication processing section 441 and/or the secondcommunication processing section 443). The programs may be programs forcausing a processor to execute the operations of the processing section440 (operations of the first communication processing section 441 and/orthe second communication processing section 443).

The second base station 400 may include a central unit (CU) and adistributed unit (DU). The CU may include the network communicationsection 420 and the second communication processing section 443 and theDU may include the wireless communication section 410 and the firstcommunication processing section 441.

Note that the second base station 400 (or the CU or DU that is a part ofthe second base station 400) may be virtualized. That is, the secondbase station 400 (or the CU or DU that is a part of the second basestation 400) may be implemented as a virtual machine. In this case, thesecond base station 400 (or the CU or DU that is a part of the secondbase station 400) (virtual machine) may operate as a virtual machine ona physical machine (hardware) including a processor, memory and the likeand on a hypervisor.

<2.2.4. Configuration of Terminal Apparatus>

FIG. 9 is a block diagram illustrating an example of a schematicconfiguration of the terminal apparatus 500 according to the firstexample embodiment. Referring to FIG. 9, the terminal apparatus 500includes a first wireless communication section 510, a second wirelesscommunication section 520, a storage section 530 and a processingsection 540.

(1) First Wireless Communication Section 510

The first wireless communication section 510 wirelessly transmits andreceives signals. For example, the first wireless communication section510 receives a signal from the first base station 100 and transmits asignal to the first base station 100.

(2) Second Wireless Communication Section 520

The second wireless communication section 520 wirelessly transmits andreceives signals. For example, the second wireless communication section520 receives a signal from the second base station 400 and transmits asignal to the second base station 400.

(3) Storage Section 530

The storage section 530 stores a program (instructions) and parametersfor operation of the terminal apparatus 500 as well as various datatemporarily or permanently. The program includes one or moreinstructions for operation of the terminal apparatus 500.

(4) Processing Section 540

The processing section 540 provides various functions of the terminalapparatus 500. The processing section 540 includes a first communicationprocessing section 541 and a second communication processing section543. Note that the processing section 540 may further include anotherconstituent element than these constituent elements. That is, theprocessing section 540 may perform operations other than the operationsof these constituent elements.

For example, the processing section 540 (the first communicationprocessing section 541) communicates with the first base station 100 viathe first wireless communication section 510. For example, theprocessing section 540 (the second communication processing section 543)communicates with the second base station 400 via the second wirelesscommunication section 520.

(5) Implementation Examples

Each of the first wireless communication section 510 and the secondwireless communication section 520 may be implemented with an antenna, ahigh frequency (RF) circuit and the like. The storage section 530 may beimplemented with a memory (for example, a non-volatile memory and/or avolatile memory), hard disc and/or the like. The processing section 540may be implemented with one or more processors such as Base Band (BB)processors, another type of processors and/or the like. The firstcommunication processing section 541 and the second communicationprocessing section 543 may be implemented with the same processor orwith respective different processors. The above memory (the storagesection 530) may be included in the one or more processors or may beexternal to the one or more processors. As an example, the processingsection 540 may be implemented in a System on Chip (SoC).

The terminal apparatus 500 may include a memory that stores programs(instructions) and one or more processors that are capable of executingthe programs (instructions). The one or more processors may execute theprograms to perform operations of the processing section 540 (operationsof the first communication processing section 541 and/or the secondcommunication processing section 543). The programs may be programs forcausing a processor to execute the operations of the processing section540 (operations of the first communication processing section 541 and/orthe second communication processing section 543).

<<2.3. Technical Features>>

Next, with reference to FIGS. 10 to 17, examples of technical featuresof the first example embodiment will be described.

(1) Counting Amount of Data

For example, the first base station 100 operates, for the terminalapparatus 500, as a secondary node (SN) of dual connectivity which usesat least NR. In this case, the first base station 100 counts an amountof data transported between the first base station 100 and the terminalapparatus 500 at RLC layer or MAC layer.

Among others, in the first example embodiment, as described above, theDU 300 (the count section 345) performs processing of RLC layer and MAClayer and, thus, the DU 300 (the count section 345) counts the amount ofdata at RLC layer or MAC layer.

Note that the term “count” may be interchanged with a term “measure”.

RLC/MAC

Specifically, for example, the DU 300 counts an amount of RLC or MACpacket data. For example, such packets may be service data units (SDU)of RLC or MAC. Alternatively, such packets may be protocol data units(PDU) of RLC or MAC.

Counted Data

For example, the data to be counted includes first data transportedbetween the first base station 100 and the terminal apparatus 500through at least one radio bearer terminated at the secondary node (SN)(that is, the first base station 100) of the dual connectivity.Moreover, for example, the data to be counted includes second datatransported between the first base station 100 and the terminalapparatus 500 through at least one radio bearer terminated at a masternode (MN) (that is, the second base station 400) of the dualconnectivity.

For example, the at least one radio bearer terminated at the SN (thefirst base station 100) includes SN Terminated bearers and the at leastone radio bearer terminated at the MN (the second base station 400)includes MN Terminated bearers. More specifically, for example, thefirst data is data transported between the first base station 100 andthe terminal apparatus 500 through a Split bearer and an SCG bearer outof the SN Terminated bearers. The second data is data transportedbetween the first base station 100 and the terminal apparatus 500through a Split bearer and an SCG bearer out of the MN Terminatedbearers.

Bearer/QoS Flow

For example, counting the amount of data is done per bearer basis. Thebearer herein may be a radio bearer (RB) (for example, data radio bearer(DRB)) or may be a radio access bearer (RAB). Alternatively, countingthe amount of data may be done per QoS flow basis.

This, for example, makes it possible for the SN to count the amount ofdata independently of bearers even if there is a complicated dataprocessing route due to various bearers. Thus, the SN can report theamount of data to the MN.

(2) Transmitting Data Amount Information by DU

For example, the DU 300 (the second communication processing section343) transmits data amount information that indicates the (counted)amount of the data.

How to Transmit

For example, the DU 300 (the second communication processing section343) transmits a signaling message including the data amount informationto the CU 200. For example, the DU 300 (the second communicationprocessing section 343) transmits the signaling message to the CU 200via the interface 60 (F1 interface).

For example, the signaling message is a DATA USAGE REPORT message. Inthe first example embodiment, the DATA USAGE REPORT message. may betransmitted in an Elementary Procedure. The Elementary Procedure is aunit representing an interaction between a gNB-CU and a gNB-DU.

For example, the data amount information corresponds to Usage countInformation Elements (IE) and, more specifically, corresponds to Usagecount UL IE and Usage count DL IE. The Usage count UL and the Usagecount DL may be referred to as Data Usage UL and Data Usage DL,respectively. The data amount information may be data usage volume.

FIGS. 10, 11 and 12 are explanatory diagrams for describing examples ofa DATA USAGE REPORT message according to the first example embodiment.FIG. 10 shows content of a DATA USAGE REPORT message where the DATAUSAGE REPORT message includes Data Usage Report list (that is, the IEthat provides information related to resources used in dual connectivityusing at least NR). FIG. 11 shows content of Data Usage Report listwhere the Data Usage Report list includes Usage count UL IE and Usagecount DL IE (that is, the counted amount of data). Note that FIG. 12provides supplementary information for FIG. 11.

This, for example, makes it possible for the CU 200 to be aware of theamount of data even if the amount of data is counted at the DU 300.

As also illustrated in FIG. 11, for example, the data amount informationincludes information per bearer (information indicative of amount ofdata per bearer basis). The bearer herein may be a radio bearer (RB)(for example, data radio bearer (DRB)) or may be a radio access bearer(RAB). Alternatively, the data amount information may includeinformation per QoS flow (information indicative of amount of data perQoS flow basis).

Transmission in Response to Instruction from CU

For example, the DU 300 (the second communication processing section343) transmits the data amount information in response to an instructionfrom the CU 200.

Specifically, for example, the CU 200 (the first communicationprocessing section 241) transmits a signaling message including aninstruction for transmission of the data amount information to the DU300. Then, the DU 300 (the second communication processing section 343)transmits the data amount information in response to that signalingmessage.

For example, the signaling message may be a UE CONTEXT SETUP REQUESTmessage or a UE CONTEXT MODIFICATION REQUEST message. For example, theinstruction may be Data Usage report Indication IE.

FIG. 13 is an explanatory diagram for describing an example of a UECONTEXT SETUP REQUEST message according to the first example embodiment.FIG. 14 is an explanatory diagram for describing an example of a UECONTEXT MODIFICATION REQUEST message according to the first exampleembodiment. Referring to FIGS. 13 and 14, each of the UE CONTEXT SETUPREQUEST message and the UE CONTEXT MODIFICATION REQUEST message (thatis, a signaling message) includes Data Usage report Indication IE(instruction for transmission of the data amount information). The DataUsage report Indication IE (instruction for transmission of the dataamount information) is a Boolean value and indicates, when it is TRUE,for example, that a signaling message including data amount informationis required.

This, for example, makes it possible for the CU 200 to control the DU300 to report the data amount information.

Note that the DU 300 (the second communication processing section 343)may not receive an instruction from the CU 200 (instruction fortransmission of data amount information) and may transmit the dataamount information without such an instruction from the CU 200. In thiscase, an Operations, Administration and Maintenance (OAM) may configuresuch as whether transmission of the data amount information (that is,data amount reporting) is to be done or not and a timing when totransmit the data amount information (that is, when to report the amountof data).

(3) Transmitting Data Amount Information by CU

For example, the CU 200 (the first communication processing section 241)receives the data amount information from the DU 300. Specifically, theCU 200 (the first communication processing section 241) receives asignaling message including the data amount information from the DU 300.

For example, the CU 200 (the second communication processing section243) transmits, to the second base station 400, a message for which thedata amount information is used.

For example, the message includes the data amount information.Alternatively, the message may include some other data amountinformation (for example, information of aggregated amount of data)generated (by the CU 200) on the basis of the received data amountinformation.

For example, the dual connectivity is EN-DC, the interface 50 betweenthe first base station 100 and the second base station 400 is an X2interface and the above message is an X2 message. More specifically, forexample, the message is a Secondary RAT Data Usage Report message.

FIGS. 15 and 16 are explanatory diagrams for describing examples of aSECONDARY RAT DATA USAGE REPORT message according to the first exampleembodiment. FIG. 15 shows contents of a SECONDARY RAT DATA USAGE REPORTmessage where the SECONDARY RAT DATA USAGE REPORT includes Secondary RATUsage Report list. FIG. 16 shows contents of the Secondary RAT UsageReport list where the Secondary RAT Usage Report list includes Usagecount UL IE and Usage count DL IE (that is, the counted amount of data).

(4) Transmitting Data Amount Information by Second Base Station

For example, the second base station 400 (the first communicationprocessing section 441) receives, from the first base station 100 (theCU 200), the message for which the data amount information is used (forexample, the message including the data amount information).

For example, the second base station 400 (the second communicationprocessing section 443) transmits, to the core network 10, the messagefor which the data amount information is used.

For example, the message transmitted to the core network 10 includes thedata amount information. Alternatively, the message transmitted to thecore network 10 may include some other data amount information (forexample, information of aggregated amount of data) generated (by the CU200 and/or the second base station 400) on the basis of the data amountinformation.

For example, the dual connectivity is EN-DC, the interface 40 betweenthe second base station 400 and the core network 10 is an S1 interfaceand the above message is an S1 message. More specifically, for example,the message is a SECONDARY RAT REPORT message and includes Usage countUL IE and Usage count DL IE (that is, the counted amount of data).

(5) Process Flow

FIG. 17 is a sequence diagram for describing an example of a schematicflow of a process according to the first example embodiment.

The CU 200 transmits, to the DU 300, a UE CONTEXT SETUP REQUEST messageor a UE CONTEXT MODIFICATION REQUEST message including Data Usage reportIndication IE (instruction for transmission of data amount information)(S601).

The DU 300 counts an amount of data transported between the first basestation 100 (SN) and the terminal apparatus 500 at RLC layer or MAClayer (S603).

The DU 300 transmits, to the CU 200, a DATA USAGE REPORT messageincluding data amount information that indicates the counted amount ofthe data (Usage count UL IE and Usage count DL IE) (S605).

The CU 200 transmits, to the second base station 400, a SECONDARY RATDATA USAGE REPORT message for which the data amount information is used(a SECONDARY RAT DATA USAGE REPORT message including Usage count UL IEand Usage count DL IE) (S607).

Note that the second base station 400 may further transmits, to the corenetwork 10, a SECONDARY RAT REPORT message for which the data amountinformation is used (a SECONDARY RAT REPORT message including Usagecount UL IE and Usage count DL IE).

The step S601 may be omitted from among the above-described processsteps. That is, as mentioned above, the DU 300 may not receive aninstruction from the CU 200 (an instruction for transmission of dataamount information) (Data Usage report Indication IE) and may transmitthe data amount information without such an instruction from the CU 200.

<<2.4. Example Alterations>>

Next, with reference to FIGS. 18 and 19, example alterations of thefirst example embodiment will be described. In the following,differences between the above-described examples in the first exampleembodiment and each example alteration will be described.

(1) Transmitting Data Amount Information by DU

How to Transmit

In the above-described example of the first example embodiment, the DU300 (the second communication processing section 343) transmits asignaling message including the data amount information to the CU 200.However, the first example embodiment is not limited to such an example.

Among others, in an example alteration of the first example embodiment,the DU 300 (the second communication processing section 343) transmits auser plane frame including the data amount information.

Specifically, for example, the DU 300 (the second communicationprocessing section 343) transmits, to the CU 200, a user plane frameincluding first data amount information indicative of an amount of firstdata transported between the first base station 100 and the terminalapparatus 500 through at least one radio bearer terminated at thesecondary node (SN) (the first base station 100) of the dualconnectivity. For example, the at least one radio bearer terminated atthe SN (the first base station 100) includes SN Terminated bearers. Forexample, the first data is data transported between the first basestation 100 and the terminal apparatus 500 through a Split bearer and anSCG bearer out of the SN Terminated bearers.

Moreover, for example, the DU 300 (the second communication processingsection 343) transmits, to the second base station 400, a user planeframe including second data amount information indicative of an amountof second data transported between the first base station 100 and theterminal apparatus 500 through at least one radio bearer terminated atthe master node (MN) (the second base station 400) of the dualconnectivity. The DU 300 (the second communication processing section343) may transmit the user plane frame including the second data amountinformation to the second base station 400 via the CU 200 or maytransmit it directly to the second base station 400 without involvingthe CU 200. For example, the at least one radio bearer terminated at theMN (the second base station 400) includes MN Terminated bearers. Forexample, the second data is data transported between the first basestation 100 and the terminal apparatus 500 through a Split bearer and anSCG bearer out of the MN Terminated bearers.

For example, the user plane frame is a GPRS Tunneling Protocol UserPlane (GTP-U) frame. Specifically, for example, the user plane frame isa DL DATA DELIVERY STATUS frame.

FIG. 18 is an explanatory diagram for describing an example of a DL DATADELIVERY STATUS frame according to an example alteration of the firstexample embodiment. Referring to FIG. 18, a DL DATA DELIVERY STATUSframe includes Data Usage UL and Data Usage DL (which may be referred toas Usage count UL and Usage count DL).

Whether each of NR user plane frames corresponding to a DL DATA DELIVERYSTATUS frame includes Data Usage UL and Data Usage DL or not may beindicated by the value of “0” or “1” of Data Usage Report IE, forexample. In a case where the frame does not include Data Usage UL andData Usage DL, that value may be “0” and, in a case where it includesData Usage UL and Data Usage DL, that value may be “1”.

Further, for example, a new PDU Type may be defined as a PDU Typeseparately from the PDU Type for a DL DATA DELIVERY STATUS frame shownin FIG. 18.

(2) Transmitting Data Amount Information by CU

For example, the CU 200 (the first communication processing section 241)receives the first data amount information from the DU 300.Specifically, the CU 200 (the first communication processing section241) receives the user plane frame including the first data amountinformation from the DU 300.

For example, the CU 200 (the second communication processing section243) transmits, to the second base station 400, a message for which thefirst data amount information is used (for example, a message includingthe first data amount information).

As such, in the example alteration of the first example embodiment, thefirst data amount information is transmitted from the DU 300 to the CU200 and, thus, the first data amount information is used for a messagetransmitted by the CU 200 to the second base station 400. Meanwhile, thesecond data amount information is transmitted from the DU 300 not to theCU 200 but to the second base station 400 and, thus, the second dataamount information is not used for the message transmitted by the CU 200to the second base station 400.

This, for example, makes it possible to restrict the report made fromthe SN to the MN to necessary and sufficient extent.

(3) Transmitting Data Amount Information by Second Base Station

For example, the second base station 400 (the first communicationprocessing section 441) receives, from the first base station 100 (theCU 200), the message for which the first data amount information is used(for example, the message including the first data amount information).The second base station 400 (the first communication processing section441) receives, from the first base station 100 (the DU 300), a userplane frame including the second data amount information.

For example, the second base station 400 (the second communicationprocessing section 443) further transmits, to the core network 10, amessage for which the first and second data amount information is used.

For example, the message transmitted to the core network 10 includes thefirst and second data amount information. Alternatively, the messagetransmitted to the core network 10 may include some other data amountinformation (for example, information of aggregated amount of data)generated (by the second base station 400) on the basis of the first andsecond data amount information.

(4) Process Flow

FIG. 19 is a sequence diagram for describing an example of a schematicflow of a process according to the example alteration of the firstexample embodiment.

The CU 200 transmits, to the DU 300, a UE CONTEXT SETUP REQUEST messageor a UE CONTEXT MODIFICATION REQUEST message including Data Usage reportIndication IE (instruction for transmission of data amount information)(S621).

The DU 300 counts an amount of data transported between the first basestation 100 (SN) and the terminal apparatus 500 at RLC layer or MAClayer (S623). Specifically, the DU 300 counts an amount of first datatransported between the first base station 100 (SN) and the terminalapparatus 500 through SN Terminated bearers and count an amount ofsecond data transported between the first base station 100 (SN) and theterminal apparatus 500 through MN Terminated bearers.

The DU 300 transmits, to the second base station 400, a DL DATA DELIVERYSTATUS frame including second data amount information that indicates thecounted amount of the second data (Usage count UL and Usage count DL)(S625). The DU 300 also transmits, to the CU 200, a DL DATA DELIVERYSTATUS frame including first data amount information that indicates thecounted amount of the first data (Usage count UL and Usage count DL)(S627).

The CU 200 transmits, to the second base station 400, a SECONDARY RATDATA USAGE REPORT message for which the first data amount information isused (a SECONDARY RAT DATA USAGE REPORT message including Usage count ULIE and Usage count DL IE) (S629).

Note that the second base station 400 may further transmits, to the corenetwork 10, a SECONDARY RAT REPORT message for which the first andsecond data amount information is used (a SECONDARY RAT REPORT messageincluding Usage count UL IE and Usage count DL IE).

The step S621 may be omitted from among the above-described processsteps. That is, as mentioned above, the DU 300 may not receive aninstruction from the CU 200 (an instruction for transmission of dataamount information) (Data Usage report Indication IE) and may transmitthe data amount information without such an instruction from the CU 200.

3. Second Example Embodiment

Next, the second example embodiment of the present invention will bedescribed with reference to FIGS. 20 to 24.

<<3.1. Splitting First Base Station>>

First, splitting the first base station 100 according to the secondexample embodiment will be described with reference to FIG. 20.

In the second example embodiment, the first base station 100 includes acentral unit 200 that performs processing of RLC and MAC layers and adistributed unit. That is, in the second example embodiment, the firstbase station 100 is split by the Lower Layer Split.

FIG. 20 is an explanatory diagram for describing an example of splittingthe first base station 100 according to the second example embodiment.Referring to FIG. 20, the CU 200 and the DU 300 included in the firstbase station 100 are shown. The PDCP, RLC and MAC layers and (upper partof) physical (PHY) layer are located at the CU 200 and (lower part of)PHY layer is located at the DU 300. That is, the CU 200 performsprocessing of the PDCP, RLC and MAC layers and (upper part of) PHY layerand the DU 300 performs processing of the (lower part of) PHY layer.

Note that, though an example of splitting the first base station 100 hasbeen described, the second base station 400 may be split similarly tothe first base station 100. Alternatively, a different splitting (forexample, Higher Layer Split) than that for the first base station 100(Lower Layer Split) may be applied to the second base station 400.

<<3.2. Configuration of Each Node>>

Next, a configuration of each node will be described with reference toFIGS. 21 and 22.

Note that the configuration of the second base station 400 according tothe second example embodiment is, for example, the same as theconfiguration of the second base station 400 according to the firstexample embodiment. The configuration of the terminal apparatus 500according to the second example embodiment is also, for example, thesame as the configuration of the terminal apparatus 500 according to thefirst example embodiment. Hence, duplicate descriptions are hereinomitted.

<3.2.1. Configuration of Central Unit (CU)>

FIG. 21 is a block diagram illustrating an example of a schematicconfiguration of the CU 200 according to the second example embodiment.Referring to FIG. 21, the CU 200 includes a first network communicationsection 210, a second network communication section 220, a storagesection 230 and a processing section 250.

There is no difference between the first and second example embodimentsin descriptions for the first network communication section 210, thesecond network communication section 220 and the storage section 230.Hence, duplicate descriptions are herein omitted.

(1) Processing Section 250

The processing section 250 provides various functions of the CU 200. Theprocessing section 250 includes a first communication processing section251, a second communication processing section 253 and a count section255. The count section 255 may also be referred to as measurementsection 255. Note that the processing section 250 may further includeanother constituent element than these constituent elements. That is,the processing section 250 may perform operations other than theoperations of these constituent elements.

For example, the processing section 250 (the first communicationprocessing section 251) communicates with the DU 300 via the firstnetwork communication section 210. For example, the processing section250 (the second communication processing section 253) communicates withthe second base station 400 (or the core network 10) via the secondnetwork communication section 220.

(2) Implementation Examples

The processing section 250 may be implemented with one or moreprocessors such as Base Band (BB) processors, another type of processorsand/or the like. The first communication processing section 251, thesecond communication processing section 253 and the count section 255may be implemented with the same processor or with respective differentprocessors. The memory (the storage section 230) may be included in theone or more processors or may be external to the one or more processors.

The CU 200 may include a memory that stores programs (instructions) andone or more processors that are capable of executing the programs(instructions). The one or more processors may execute the programs toperform operations of the processing section 250 (operations of thefirst communication processing section 251, the second communicationprocessing section 253 and/or the count section 255). The programs maybe programs for causing a processor to execute the operations of theprocessing section 250 (operations of the first communication processingsection 251, the second communication processing section 253 and/or thecount section 255).

Note that the CU 200 may be virtualized. That is, the CU 200 may beimplemented as a virtual machine. In this case, the CU 200 (virtualmachine) may operate as a virtual machine on a physical machine(hardware) including a processor, memory and the like and on ahypervisor.

<3.2.2. Configuration of Distributed Unit (DU)>

FIG. 22 is a block diagram illustrating an example of a schematicconfiguration of the DU 300 according to the second example embodiment.Referring to FIG. 22, the DU 300 includes a wireless communicationsection 310, a network communication section 320, a storage section 330and a processing section 350.

There is no difference between the first and second example embodimentsin descriptions for the wireless communication section 310, the networkcommunication section 320 and the storage section 330. Hence, duplicatedescriptions are herein omitted.

(1) Processing Section 350

The processing section 350 provides various functions of the DU 300. Theprocessing section 350 includes a first communication processing section351 and a second communication processing section 353. Note that theprocessing section 350 may further include another constituent elementthan these constituent elements. That is, the processing section 350 mayperform operations other than the operations of these constituentelements.

For example, the processing section 350 (the first communicationprocessing section 351) communicates with the terminal apparatus 500 viathe wireless communication section 310. For example, the processingsection 350 (the second communication processing section 353)communicates with the CU 200 (or the second base station 400) via thenetwork communication section 320.

(2) Implementation Examples

The processing section 350 may be implemented with one or moreprocessors such as Base Band (BB) processors, another type of processorsand/or the like. The first communication processing section 351 and thesecond communication processing section 353 may be implemented with thesame processor or with respective different processors. The memory (thestorage section 330) may be included in the one or more processors ormay be external to the one or more processors.

The DU 300 may include a memory that stores programs (instructions) andone or more processors that are capable of executing the programs(instructions). The one or more processors may execute the programs toperform operations of the processing section 350 (operations of thefirst communication processing section 351 and/or the secondcommunication processing section 353). The programs may be programs forcausing a processor to execute the operations of the processing section350 (operations of the first communication processing section 351 and/orthe second communication processing section 353).

Note that the DU 300 may be virtualized. That is, the DU 300 may beimplemented as a virtual machine. In this case, the DU 300 (virtualmachine) may operate as a virtual machine on a physical machine(hardware) including a processor, memory and the like and on ahypervisor.

<<3.3. Technical Features>>

Next, with reference to FIG. 23, examples of technical features of thesecond example embodiment will be described.

(1) Counting Amount of Data

For example, the first base station 100 operates, for the terminalapparatus 500, as a secondary node (SN) of dual connectivity which usesat least NR. In this case, the first base station 100 counts an amountof data transported between the first base station 100 and the terminalapparatus 500 at RLC layer or MAC layer.

Among others, in the second example embodiment, as described above, theCU 200 performs processing of RLC layer and MAC layer and, thus, the CU200 (the count section 255) counts the amount of data at RLC layer orMAC layer.

Note that the term “count” may be interchanged with a term “measure”.

RLC/MAC

Specifically, for example, the CU 200 (the count section 255) counts anamount of RLC or MAC packet data. For example, such packets may beservice data units (SDU) of RLC or MAC. Alternatively, such packets maybe protocol data units (PDU) of RLC or MAC.

Counted Data

There is no difference between the first and second example embodimentsin descriptions for counted data. Hence, duplicate descriptions areherein omitted.

Bearer/QoS Flow

For example, counting the amount of data is done per bearer basis. Thebearer herein may be a radio bearer (RB) (for example, data radio bearer(DRB)) or may be a radio access bearer (RAB). Alternatively, countingthe amount of data may be done per QoS flow basis.

This, for example, makes it possible for the SN to count the amount ofdata independently of bearers even if there is a complicated dataprocessing route due to various bearers. Thus, the SN can report theamount of data to the MN.

(2) Transmitting Data Amount Information by CU

For example, the CU 200 (the second communication processing section253) transmits, to the second base station 400 (MN), data amountinformation that indicates the (counted) amount of the data.

For example, the CU 200 (the second communication processing section253) transmits, to the second base station 400 (MN), a message includingthe data amount information.

For example, the dual connectivity is EN-DC, the interface 50 betweenthe first base station 100 and the second base station 400 is an X2interface and the above message is an X2 message. More specifically, forexample, the message is a Secondary RAT Data Usage Report message.

For example, there is no difference between the first and second exampleembodiments in descriptions for contents of the SECONDARY RAT DATA USAGEREPORT message (FIGS. 15 and 16). Hence, duplicate descriptions areherein omitted.

As also illustrated in FIG. 16, for example, the data amount informationincludes information per bearer (information indicative of amount ofdata per bearer basis). The bearer herein may be a radio bearer (RB)(for example, data radio bearer (DRB)) or may be a radio access bearer(RAB) (for example, E-RAB). Alternatively, the data amount informationmay include information per QoS flow (information indicative of amountof data per QoS flow basis).

(3) Transmitting Data Amount Information by Second Base Station

For example, the second base station 400 (the first communicationprocessing section 441) receives, from the first base station 100 (theCU 200), the message including the data amount information.

For example, the second base station 400 (the second communicationprocessing section 443) further transmits, to the core network 10, amessage for which the data amount information is used.

For example, the message transmitted to the core network 10 includes thedata amount information. Alternatively, the message transmitted to thecore network 10 may include some other data amount information (forexample, information of aggregated amount of data) generated (by thesecond base station 400) on the basis of the data amount information.

For example, the dual connectivity is EN-DC, the interface 40 betweenthe second base station 400 and the core network 10 is an S1 interfaceand the above message is an S1 message. More specifically, for example,the message is a SECONDARY RAT REPORT message and includes Usage countUL IE and Usage count DL IE (that is, the counted amount of data).

(4) Process Flow

FIG. 23 is a sequence diagram for describing an example of a schematicflow of a process according to the second example embodiment.

The CU 200 counts an amount of data transported between the first basestation 100 (SN) and the terminal apparatus 500 at RLC layer or MAClayer (S641).

The CU 200 transmits, to the second base station 400, a SECONDARY RATDATA USAGE REPORT message including data amount information thatindicates the counted amount of the data (Usage count UL IE and Usagecount DL IE) (S643).

Note that the second base station 400 may further transmits, to the corenetwork 10, a SECONDARY RAT REPORT message for which the data amountinformation is used (a SECONDARY RAT REPORT message including Usagecount UL IE and Usage count DL IE).

<<3.4. Example Alterations>>

Next, with reference to FIG. 24, example alterations of the secondexample embodiment will be described. In the following, differencesbetween the above-described examples in the second example embodimentand each example alteration will be described.

(1) Transmitting Data Amount Information by CU

In the above-described example of the second example embodiment, the CU200 (the second communication processing section 243) transmits amessage (a control plane message) including the data amount informationto the second base station 400 (MN). However, the second exampleembodiment is not limited to such an example.

Among others, in an example alteration of the second example embodiment,the CU 200 (the second communication processing section 243) transmits auser plane frame including the data amount information to the secondbase station 400 (MN).

Specifically, for example, the CU 200 (the second communicationprocessing section 243) transmits, to the second base station 400 (MN),a user plane frame including first data amount information indicative ofan amount of first data transported between the first base station 100and the terminal apparatus 500 through at least one radio bearerterminated at the secondary node (SN) (the first base station 100) ofthe dual connectivity. For example, the at least one radio bearerterminated at the SN (the first base station 100) includes SN Terminatedbearers. For example, the first data is data transported between thefirst base station 100 and the terminal apparatus 500 through a Splitbearer and an SCG bearer out of the SN Terminated bearers.

Moreover, for example, the CU 200 (the second communication processingsection 243) transmits, to the second base station 400 (MN), a userplane frame including second data amount information indicative of anamount of second data transported between the first base station 100 andthe terminal apparatus 500 through at least one radio bearer terminatedat the master node (MN) (the second base station 400) of the dualconnectivity. For example, the at least one radio bearer terminated atthe MN (the second base station 400) includes MN Terminated bearers. Forexample, the second data is data transported between the first basestation 100 and the terminal apparatus 500 through a Split bearer and anSCG bearer out of the MN Terminated bearers.

For example, the user plane frame is a GTP-U frame. Specifically, forexample, the user plane frame is a DL DATA DELIVERY STATUS frame.

For example, there is no difference between the first and second exampleembodiments in descriptions for contents of the DL DATA DELIVERY STATUSframe (FIG. 18). Hence, duplicate descriptions are herein omitted.

(2) Transmitting Data Amount Information by Second Base Station

For example, the second base station 400 (the first communicationprocessing section 441) receives, from the first base station 100 (theCU 200), the message including the first data amount information. Thesecond base station 400 (the first communication processing section 441)receives, from the first base station 100 (the CU 200), a user planeframe including the second data amount information.

For example, the second base station 400 (the second communicationprocessing section 443) further transmits, to the core network 10, amessage for which the first and second data amount information is used.

For example, the message transmitted to the core network 10 includes thefirst and second data amount information. Alternatively, the messagetransmitted to the core network 10 may include some other data amountinformation (for example, information of aggregated amount of data)generated (by the second base station 400) on the basis of the first andsecond data amount information.

(3) Process Flow

FIG. 24 is a sequence diagram for describing an example of a schematicflow of a process according to the example alteration of the secondexample embodiment.

The CU 200 counts an amount of data transported between the first basestation 100 (SN) and the terminal apparatus 500 at RLC layer or MAClayer (S661). Specifically, the CU 200 counts an amount of first datatransported between the first base station 100 (SN) and the terminalapparatus 500 through SN Terminated bearers and count an amount ofsecond data transported between the first base station 100 (SN) and theterminal apparatus 500 through MN Terminated bearers.

The CU 200 transmits, to the second base station 400, a DL DATA DELIVERYSTATUS frame including second data amount information that indicates thecounted amount of the second data (Usage count UL and Usage count DL)(S663).

The CU 200 transmits, to the second base station 400, a SECONDARY RATDATA USAGE REPORT message including the first data amount informationthat indicates the counted amount of the first data (Usage count UL IEand Usage count DL IE) (S665).

Note that the second base station 400 may further transmits, to the corenetwork 10, a SECONDARY RAT REPORT message for which the first andsecond data amount information is used (a SECONDARY RAT REPORT messageincluding Usage count UL IE and Usage count DL IE).

4. Third Example Embodiment

Next, the third example embodiment of the present invention will bedescribed with reference to FIGS. 25 to 32.

<<4.1. Splitting First Base Station>>

First, splitting the first base station 100 according to the thirdexample embodiment will be described with reference to FIGS. 25 and 26.

FIG. 25 is an explanatory diagram for describing an example of splittingthe first base station 100 according to the third example embodiment.Referring to FIG. 25, the first base station 100 includes a central unit(CU) 200 and distributed units (DUs) 300. Further, in the third exampleembodiment, the CU 200 includes a CU-CP 201 which is a first centralunit for a control plane and a CU-UP 203 which is a second central unitfor a user plane. There may exist a plurality of CU-UPs 203 per a singleCU-CP 201. Each DU 300 communicates with the CU-CP 201 via an interface61 and with the CU-UP 203 via an interface 63.

For example, the CU 200 performs processing of the PDCP layer and the DU300 performs processing of RLC and MAC layers. That is, the first basestation 100 is split by Higher Layer Split.

FIG. 26 is an explanatory diagram for describing an example of splittingthe first base station 100 (higher layer split) according to the thirdexample embodiment. Referring to FIG. 26, the CU 200 and the DU 300included in the first base station 100 are shown. The PDCP layer islocated at the CU 200 and the RLC, MAC and physical (PHY) layers arelocated at the DU 300. That is, the CU 200 performs processing of thePDCP layer and the DU 300 performs processing of the RLC, MAC and PHYlayers. Further, the control plane in the PDCP layer is located at theCU-CP 201 and the user plane in the PDCP layer is located at the CU-UP203. In this case, the interface 61 is an F1-C interface and theinterface 63 is an F1-U interface.

Alternatively, in the third example embodiment, the CU 200 may performprocessing of PDCP layer and processing of RLC and MAC layers. That is,the first base station 100 may be split by Lower Layer Split.

<<4.2. Configuration of Each Node>>

Next, a configuration of each node will be described with reference toFIGS. 27 and 28.

Note that the configuration of the DU 300 according to the third exampleembodiment is, for example, the same as the configuration of the DU 300according to the first or second example embodiment. The configurationsof the second base station 400 and the terminal apparatus 500 accordingto the third example embodiment are also, for example, the same as theconfigurations of the second base station 400 and the terminal apparatus500 according to the first (or second) example embodiment. Hence,duplicate descriptions are herein omitted.

<4.2.1. Configuration of CU-CP>

FIG. 27 is a block diagram illustrating an example of a schematicconfiguration of the CU-CP 201 according to the third exampleembodiment. Referring to FIG. 27, the CU-CP 201 includes a first networkcommunication section 211, a second network communication section 221, astorage section 231 and a processing section 260.

(1) First Network Communication Section 211

The first network communication section 211 receives a signal from theCU-UP 203 and transmits a signal to the CU-UP 203.

The first network communication section 211 may receive a signal fromthe DU 300 and transmit a signal to the DU 300.

(2) Second Network Communication Section 221

The second network communication section 221 receives a signal from thesecond base station 400 and transmits a signal to the second basestation 400.

The second network communication section 221 may receive a signal fromthe core network 10 and transmit a signal to the core network 10.

(3) Storage Section 231

The storage section 231 stores a program (instructions) and parametersfor operation of the CU-CP 201 as well as various data temporarily orpermanently. The program includes one or more instructions for operationof the CU-CP 201.

(4) Processing Section 260

The processing section 260 provides various functions of the CU-CP 201.The processing section 260 includes a first communication processingsection 261 and a second communication processing section 263. Note thatthe processing section 260 may further include another constituentelement than these constituent elements. That is, the processing section260 may perform operations other than the operations of theseconstituent elements.

For example, the processing section 260 (the first communicationprocessing section 261) communicates with the CU-UP 203 (or the DU 300)via the first network communication section 211. For example, theprocessing section 260 (the second communication processing section 263)communicates with the second base station 400 (or the core network 10)via the second network communication section 221.

(5) Implementation Examples

Each of the first network communication section 211 and the secondnetwork communication section 221 may be implemented with a networkadapter, a network interface card and/or the like. The storage section231 may be implemented with a memory (for example, a non-volatile memoryand/or a volatile memory), hard disc and/or the like. The processingsection 260 may be implemented with one or more processors such as BaseBand (BB) processors, another type of processors and/or the like. Thefirst communication processing section 261 and the second communicationprocessing section 263 may be implemented with the same processor orwith respective different processors. The above memory (the storagesection 231) may be included in the one or more processors or may beexternal to the one or more processors.

The CU-CP 201 may include a memory that stores programs (instructions)and one or more processors that are capable of executing the programs(instructions). The one or more processors may execute the programs toperform operations of the processing section 260 (operations of thefirst communication processing section 261 and/or the secondcommunication processing section 263). The programs may be programs forcausing a processor to execute the operations of the processing section260 (operations of the first communication processing section 261 and/orthe second communication processing section 263).

Note that the CU-CP 201 may be virtualized. That is, the CU-CP 201 maybe implemented as a virtual machine. In this case, the CU-CP 201(virtual machine) may operate as a virtual machine on a physical machine(hardware) including a processor, memory and the like and on ahypervisor.

<4.2.2. Configuration of CU-CP>

FIG. 28 is a block diagram illustrating an example of a schematicconfiguration of the CU-UP 203 according to the third exampleembodiment. Referring to FIG. 28, the CU-UP 203 includes a first networkcommunication section 213, a second network communication section 223, astorage section 233 and a processing section 270.

(1) First Network Communication Section 213

The first network communication section 213 receives a signal from theCU-CP 201 and transmits a signal to the CU-CP 201.

The first network communication section 213 may receive a signal fromthe DU 300 and transmit a signal to the DU 300.

(2) Second Network Communication Section 223

The second network communication section 223 receives a signal from thesecond base station 400 and transmits a signal to the second basestation 400.

The second network communication section 223 may receive a signal fromthe core network 10 and transmit a signal to the core network 10.

(3) Storage Section 233

The storage section 233 stores a program (instructions) and parametersfor operation of the CU-UP 203 as well as various data temporarily orpermanently. The program includes one or more instructions for operationof the CU-UP 203.

(4) Processing Section 270

The processing section 270 provides various functions of the CU-UP 203.The processing section 270 includes a first communication processingsection 271 and a second communication processing section 273. Note thatthe processing section 270 may further include another constituentelement than these constituent elements. That is, the processing section270 may perform operations other than the operations of theseconstituent elements.

For example, the processing section 270 (the first communicationprocessing section 271) communicates with the CU-CP 201 (or the DU 300)via the first network communication section 213. For example, theprocessing section 270 (the second communication processing section 273)communicates with the second base station 400 (or the core network 10)via the second network communication section 223.

(5) Implementation Examples

Each of the first network communication section 213 and the secondnetwork communication section 223 may be implemented with a networkadapter, a network interface card and/or the like. The storage section233 may be implemented with a memory (for example, a non-volatile memoryand/or a volatile memory), hard disc and/or the like. The processingsection 270 may be implemented with one or more processors such as BaseBand (BB) processors, another type of processors and/or the like. Thefirst communication processing section 271 and the second communicationprocessing section 273 may be implemented with the same processor orwith respective different processors. The above memory (the storagesection 233) may be included in the one or more processors or may beexternal to the one or more processors.

The CU-UP 203 may include a memory that stores programs (instructions)and one or more processors that are capable of executing the programs(instructions). The one or more processors may execute the programs toperform operations of the processing section 270 (operations of thefirst communication processing section 271 and/or the secondcommunication processing section 273). The programs may be programs forcausing a processor to execute the operations of the processing section270 (operations of the first communication processing section 271 and/orthe second communication processing section 273).

Note that the CU-UP 203 may be virtualized. That is, the CU-UP 203 maybe implemented as a virtual machine. In this case, the CU-UP 203(virtual machine) may operate as a virtual machine on a physical machine(hardware) including a processor, memory and the like and on ahypervisor.

<<4.3. Technical Features>>

Next, with reference to FIGS. 29 to 32, examples of technical featuresof the third example embodiment will be described.

The descriptions in the first and second example embodiments may beapplied where appropriate in the third example embodiment. In thefollowing, specific process flows will be described.

(1) Process Flow (First Example)

FIG. 29 is a sequence diagram for describing a first example of aschematic flow of a process according to the third example embodiment.

The CU-CP 201 (the first communication processing section 261)transmits, to the DU 300, a UE CONTEXT SETUP REQUEST message or a UECONTEXT MODIFICATION REQUEST message including Data Usage reportIndication IE (instruction for transmission of data amount information)(S701).

The DU 300 (the count section 345) counts an amount of data transportedbetween the first base station 100 (SN) and the terminal apparatus 500(S703). For example, the DU 300 counts the amount of the data at RLClayer or MAC layer. For example, the DU 300 (the count section 345)counts an amount of first data transported through SN Terminated bearersand an amount of second data transported through MN Terminated bearers.

The DU 300 (the second communication processing section 343) transmitsdata amount information that indicates the counted amount of data to theCU-UP 203 (S705). For example, the DU 300 transmits a user plane frameincluding the data amount information to the CU-UP 203.

The CU-UP 203 (the first communication processing section 271) transmitsthe data amount information to the CU-CP 201 (S707).

The CU-CP 201 (the second communication processing section 263)transmits, to the second base station 400, a SECONDARY RAT DATA USAGEREPORT message for which the data amount information is used (aSECONDARY RAT DATA USAGE REPORT message including Usage count UL IE andUsage count DL IE) (S709).

Note that the second base station 400 may further transmits, to the corenetwork 10, a SECONDARY RAT REPORT message for which the data amountinformation is used (a SECONDARY RAT REPORT message including Usagecount UL IE and Usage count DL IE).

The step S701 may be omitted from among the above-described processsteps. That is, as mentioned above, the DU 300 may not receive aninstruction from the CU 200 (an instruction for transmission of dataamount information) (Data Usage report Indication IE) and may transmitthe data amount information without such an instruction from the CU 200(see the first and second example embodiments).

(2) Process Flow (Second Example)

FIG. 30 is a sequence diagram for describing a second example of aschematic flow of a process according to the third example embodiment.

The CU-CP 201 (the first communication processing section 261)transmits, to the DU 300, a UE CONTEXT SETUP REQUEST message or a UECONTEXT MODIFICATION REQUEST message including Data Usage reportIndication IE (instruction for transmission of data amount information)(S721).

The DU 300 (the count section 345) counts an amount of data transportedbetween the first base station 100 (SN) and the terminal apparatus 500(S723). For example, the DU 300 counts the amount of the data at RLClayer or MAC layer. For example, the DU 300 (the count section 345)counts an amount of first data transported through SN Terminated bearersand count an amount of second data transported through MN Terminatedbearers.

The DU 300 (the second communication processing section 343) transmits,to the second base station 400 (MN), second data amount information thatindicates the counted amount of the second data (S725). For example, theDU 300 transmits a user plane frame including the second data amountinformation to the second base station 400.

The DU 300 (the second communication processing section 343) transmits,to the CU-UP 203, first data amount information that indicates thecounted amount of the first data (S727). For example, the DU 300transmits a user plane frame including the first data amount informationto CU-UP 203.

The CU-UP 203 (the first communication processing section 271) transmitsthe first data amount information to the CU-CP 201 (S729).

The CU-CP 201 (the second communication processing section 263)transmits, to the second base station 400, a SECONDARY RAT DATA USAGEREPORT message for which the first data amount information is used (aSECONDARY RAT DATA USAGE REPORT message including Usage count UL IE andUsage count DL IE) (S731).

Note that the second base station 400 may further transmits, to the corenetwork 10, a SECONDARY RAT REPORT message for which the first andsecond data amount information is used (a SECONDARY RAT REPORT messageincluding Usage count UL IE and Usage count DL IE).

The step S721 may be omitted from among the above-described processsteps. That is, as mentioned above, the DU 300 may not receive aninstruction from the CU 200 (an instruction for transmission of dataamount information) (Data Usage report Indication IE) and may transmitthe data amount information without such an instruction from the CU 200(see the first and second example embodiments).

(3) Process Flow (Third Example)

FIG. 31 is a sequence diagram for describing a third example of aschematic flow of a process according to the third example embodiment.

In this case, the processing section 270 of the CU-UP 203 furtherincludes a count section 275 (a measurement section 275).

The CU-UP 203 (the count section 275) counts an amount of datatransported between the first base station 100 (SN) and the terminalapparatus 500 (S741). For example, the CU-UP 203 (the count section 275)counts an amount of first data transported through SN Terminatedbearers. The CU-UP 203 (the count section 275) may count an amount ofsecond data transported through MN Terminated bearers. For example, theCU-UP 203 (the count section 275) counts the amount of the first data(and the amount of the second data) between PDCP layer and RLC layer.Alternatively, the CU-UP 203 (the count section 275) may count theamount of the first data (and the amount of the second data) at RLC orMAC layer (in the case of Lower Layer Split).

The CU-UP 203 (the first communication processing section 271) transmitsdata amount information indicative of the counted amount of data to theCU-CP 201 (S743).

The CU-CP 201 (the second communication processing section 263)transmits, to the second base station 400, a SECONDARY RAT DATA USAGEREPORT message for which the data amount information is used (aSECONDARY RAT DATA USAGE REPORT message including Usage count UL IE andUsage count DL IE) (S745).

Note that the second base station 400 may further transmits, to the corenetwork 10, a SECONDARY RAT REPORT message for which the data amountinformation is used (a SECONDARY RAT REPORT message including Usagecount UL IE and Usage count DL IE).

The CU-UP 203 may transmit the data amount information to the CU-CP 201in response to an instruction from the CU-CP 201 (an instruction fortransmission of data amount information). Alternatively, the CU-UP 203may transmit the data amount information to the CU-CP 201 without aninstruction from the CU-CP 201. In this case, an OAM may configure suchas whether transmission of the data amount information (that is, dataamount reporting) is to be done or not and a timing when to transmit thedata amount information (that is, when to report the amount of data).

(4) Process Flow (Fourth Example)

FIG. 32 is a sequence diagram for describing a fourth example of aschematic flow of a process according to the third example embodiment.

In this case, the processing section 270 of the CU-UP 203 furtherincludes a count section 275 (a measurement section 275).

The CU-UP 203 (the count section 275) counts an amount of datatransported between the first base station 100 (SN) and the terminalapparatus 500 (S761). For example, the CU-UP 203 (the count section 275)counts an amount of first data transported through SN Terminated bearersand an amount of second data transported through MN Terminated bearers.For example, the CU-UP 203 (the count section 275) counts the amount ofthe first data and the amount of the second data between PDCP layer andRLC layer. Alternatively, the CU-UP 203 (the count section 275) maycount the amount of the first data and the amount of the second data atRLC or MAC layer (in the case of Lower Layer Split).

The CU-UP 203 (the second communication processing section 273)transmits second data amount information indicative of the countedamount of the second data to the second base station 400 (MN) (S763).For example, the CU-UP 203 transmits a user plane frame including thesecond data amount information to the second base station 400.

The CU-UP 203 (the first communication processing section 271) transmitsfirst data amount information indicative of the counted amount of thefirst data to the CU-CP 201 (S765).

The CU-CP 201 (the second communication processing section 263)transmits, to the second base station 400, a SECONDARY RAT DATA USAGEREPORT message for which the first data amount information is used (aSECONDARY RAT DATA USAGE REPORT message including Usage count UL IE andUsage count DL IE) (S767).

Note that the second base station 400 may further transmits, to the corenetwork 10, a SECONDARY RAT REPORT message for which the first andsecond data amount information is used (a SECONDARY RAT REPORT messageincluding Usage count UL IE and Usage count DL IE).

The CU-UP 203 may transmit the data amount information in response to aninstruction from the CU-CP 201 (an instruction for transmission of dataamount information). Alternatively, the CU-UP 203 may transmit the dataamount information without an instruction from the CU-CP 201. In thiscase, an OAM may configure such as whether transmission of the dataamount information (that is, data amount reporting) is to be done or notand a timing when to transmit the data amount information (that is, whento report the amount of data).

5. Fourth Example Embodiment

Next, the fourth example embodiment of the present invention will bedescribed with reference to FIGS. 33 to 35. The foregoing first, secondand third example embodiments are concrete embodiments whereas thefourth example embodiment is a more generalized embodiment.

<<5.1. Configuration of Each Node>>

First, a configuration of each node will be described with reference toFIGS. 33 to 35.

<5.1.1. Configuration of First Communication Apparatus>

FIG. 33 is a block diagram illustrating an example of a schematicconfiguration of a first communication apparatus 1100 according to thefourth example embodiment. Referring to FIG. 33, the first communicationapparatus 1100 includes a communication processing section 1110.Specific actions of the communication processing section 1110 will bedescribed later.

The communication processing section 1110 may be implemented with one ormore processors such as Base Band (BB) processors, another type ofprocessors and/or the like and a memory (for example, a non-volatilememory and/or a volatile memory), hard disc and/or the like. The memorymay be included in the one or more processors or may be external to theone or more processors.

The first communication apparatus 1100 may include a memory that storesprograms (instructions) and one or more processors that are capable ofexecuting the programs (instructions). The one or more processors mayexecute the programs to perform operations of the communicationprocessing section 1110. The programs may be programs for causing aprocessor to execute the operations of the communication processingsection 1110.

Note that the first communication apparatus 1100 may be virtualized.That is, the first communication apparatus 1100 may be implemented as avirtual machine. In this case, the first communication apparatus 1100(virtual machine) may operate as a virtual machine on a physical machine(hardware) including a processor, memory and the like and on ahypervisor.

<5.1.2. Configuration of Second Communication Apparatus>

FIG. 34 is a block diagram illustrating an example of a schematicconfiguration of a second communication apparatus 1200 according to thefourth example embodiment. Referring to FIG. 34, the secondcommunication apparatus 1200 includes a first communication processingsection 1210 and a second communication processing section 1220.Specific actions of the first communication processing section 1210 andthe second communication processing section 1220 will be describedlater.

The first communication processing section 1210 and the secondcommunication processing section 1220 may be implemented with one ormore processors such as Base Band (BB) processors, another type ofprocessors and/or the like and a memory (for example, a non-volatilememory and/or a volatile memory), hard disc and/or the like. The memorymay be included in the one or more processors or may be external to theone or more processors.

The second communication apparatus 1200 may include a memory that storesprograms (instructions) and one or more processors that are capable ofexecuting the programs (instructions). The one or more processors mayexecute the programs to perform operations of the first communicationprocessing section 1210 and/or the second communication processingsection 1220. The programs may be programs for causing a processor toexecute the operations of the first communication processing section1210 and/or the second communication processing section 1220.

Note that the second communication apparatus 1200 may be virtualized.That is, the second communication apparatus 1200 may be implemented as avirtual machine. In this case, the second communication apparatus 1200(virtual machine) may operate as a virtual machine on a physical machine(hardware) including a processor, memory and the like and on ahypervisor.

<5.1.3. Configuration of Terminal Apparatus>

FIG. 35 is a block diagram illustrating an example of a schematicconfiguration of a terminal apparatus 1300 according to the fourthexample embodiment. Referring to FIG. 35, the terminal apparatus 1300includes a first communication processing section 1310 and a secondcommunication processing section 1320. Specific actions of the firstcommunication processing section 1310 and the second communicationprocessing section 1320 will be described later.

The first communication processing section 1310 and the secondcommunication processing section 1320 may be implemented with one ormore processors such as Base Band (BB) processors, another type ofprocessors and/or the like and a memory (for example, a non-volatilememory and/or a volatile memory), hard disc and/or the like. The memorymay be included in the one or more processors or may be external to theone or more processors.

The terminal apparatus 1300 may include a memory that stores programs(instructions) and one or more processors that are capable of executingthe programs (instructions). The one or more processors may execute theprograms to perform operations of the first communication processingsection 1310 and/or the second communication processing section 1320.The programs may be programs for causing a processor to execute theoperations of the first communication processing section 1310 and/or thesecond communication processing section 1320.

<<5.2. Technical Features>>

Next, examples of technical features of the fourth example embodimentwill be described.

(1) First Communication Apparatus 1100

The first communication apparatus 1100 (the communication processingsection 1110) is configured to transmit data amount information to acentral unit included in a first base station, the data amountinformation being indicative of an amount of data transported betweenthe first base station and a terminal apparatus, the first base stationoperating, for the terminal apparatus, as a secondary node of dualconnectivity using at least NR.

As a first example, the first base station includes the central unit anda distributed unit and the first communication apparatus 1100 is thedistributed unit. Specifically, for example, the first communicationapparatus 1100 is the DU 300 of the first example embodiment and thecommunication processing section 1110 is the second communicationprocessing section 343 of the DU 300 of the first example embodiment.

As a second example, the central unit may be a CU-CP (a first centralunit for a control plane) included in the first base station and thefirst communication apparatus 1100 may be a CU-UP (a second central unitfor a user plane) included in the first base station. Specifically, forexample, the central unit may be the CU-CP 201 of the third exampleembodiment, the first communication apparatus 1100 may be the CU-UP 203of the third example embodiment and the communication processing section1110 may be the first communication processing section 271 of the CU-UP203 of the third example embodiment.

As a third example, the first communication apparatus 1100 may be thefirst base station. Specifically, for example, the first communicationapparatus 1100 may be the first base station 100 of the first exampleembodiment and the communication processing section 1110 may be thesecond communication processing section 343 of the DU 300 included inthe first base station of the first example embodiment. Alternatively,the first communication apparatus 1100 may be the first base station 100of the third example embodiment and the communication processing section1110 may be the first communication processing section 271 of the CU-UP203 of the third example embodiment.

This, for example, makes it possible for the SN (central unit) to reportan amount of data to the MN.

(2) Second Communication Apparatus 1200

The second communication apparatus 1200 (the first communicationprocessing section 1210) is configured to receive the data amountinformation from a unit included in the first base station. The secondcommunication apparatus 1200 (the second communication processingsection 1220) is configured to transmit a message for which the dataamount information is used to a second base station operating as amaster node of the dual connectivity.

As a first example, the unit is the distributed unit included in thefirst base station and the second communication apparatus 1200 is thecentral unit included in the first base station. Specifically, forexample, the unit is the DU 300 of the first example embodiment, thesecond communication apparatus 1200 is the CU 200 of the first exampleembodiment and the first communication processing section 1210 and thesecond communication processing section 1220 are the first communicationprocessing section 241 and the second communication processing section243 of the CU 200 of the first example embodiment.

As a second example, the unit may be a CU-UP (a second central unit fora user plane) included in the first base station and the secondcommunication apparatus 1200 may be a CU-CP (a first central unit for acontrol plane) included in the first base station. Specifically, forexample, the unit may be the CU-UP 203 of the third example embodiment,the second communication apparatus 1200 may be the CU-CP 201 of thethird example embodiment and the first communication processing section1210 and the second communication processing section 1220 may be thefirst communication processing section 261 and the second communicationprocessing section 263 of the CU-CP 201 of the third example embodiment.

As a third example, the second communication apparatus 1200 may be thefirst base station. Specifically, for example, the second communicationapparatus 1200 may be the first base station 100 of the first exampleembodiment and the first communication processing section 1210 and thesecond communication processing section 1220 may be the firstcommunication processing section 241 and the second communicationprocessing section 243 of the CU 200 included in the first base stationof the first example embodiment. Alternatively, the second communicationapparatus 1200 may be the first base station 100 of the third exampleembodiment and the first communication processing section 1210 and thesecond communication processing section 1220 may be the firstcommunication processing section 261 and the second communicationprocessing section 263 of the CU-CP 201 included in the first basestation 100 of the third example embodiment.

(3) Terminal Apparatus 1300

The terminal apparatus 1300 (the first communication processing section1310) is configured to communicate with the first base station. Theterminal apparatus 1300 (the second communication processing section1320) is configured to communicate with the second base station.

For example, the terminal apparatus 1300 is the terminal apparatus 500of the first, second or third example embodiment and the firstcommunication processing section 1310 and the second communicationprocessing section 1320 are the first communication processing section541 and the second communication processing section 543 of the terminalapparatus 500.

Note that the fourth example embodiment is not limited to the abovedescribed examples.

Though example embodiments of the present disclosure have been describedherein, the present disclosure is not limited to these exampleembodiments. It will be understood by those of ordinary skill in the artthat these example embodiments are illustrative only and that variousalterations can be done without departing from the scope and spirit ofthe present disclosure.

For example, the steps in processes described in the presentspecification may not necessarily be performed chronologically in theorder illustrated in the sequence diagrams. For example, steps in aprocess may be performed in a different order than the order illustratedin a sequence diagram or may be performed in parallel. Some of steps ina process may be removed or further steps may be added to a process.

Moreover, an apparatus (one of sub-apparatuses constituting a node or amodule for the node or the sub-apparatus) including constituent elements(for example, a communication processing section and/or a count section)of a node (the first base station, CU, DU, second base station orterminal apparatus) described in the present specification may beprovided. In addition, methods including processes of such constituentelements may be provided, and programs for causing processors to executeprocesses of such constituent elements may be provided. Furthermore,computer-readable non-transitory recording media (non-transitorycomputer readable media) having recorded thereon such programs may beprovided. It is apparent that such sub-apparatuses, modules, methods,programs and computer-readable non-transitory recording media are alsoincluded in the present disclosure.

Some or all of the above-described example embodiments can be describedas in the following Supplementary Notes, but are not limited to thefollowing.

(Supplementary Note 1)

A communication apparatus comprising:

a communication processing section configured to transmit data amountinformation to a central unit included in a first base station, the dataamount information being indicative of an amount of data transportedbetween the first base station and a terminal apparatus, the first basestation operating, for the terminal apparatus, as a secondary node ofdual connectivity using at least New Radio (NR).

(Supplementary Note 2)

The communication apparatus according to Supplementary Note 1, whereinthe data includes first data transported between the first base stationand the terminal apparatus through at least one radio bearer terminatedat the secondary node.

(Supplementary Note 3)

The communication apparatus according to Supplementary Note 2, wherein:

the at least one radio bearer terminated at the secondary node includesSN Terminated bearers; and

the first data is data transported between the first base station andthe terminal apparatus through a Split bearer and an SCG bearer out ofthe SN Terminated bearers.

(Supplementary Note 4)

The communication apparatus according to Supplementary Note 2 or 3,wherein the data further incudes second data transported between thefirst base station and the terminal apparatus through at least one radiobearer terminated at a master node of the dual connectivity.

(Supplementary Note 5)

The communication apparatus according to Supplementary Note 4, wherein:

the at least one radio bearer terminated at the master node includes MNTerminated bearers; and

the second data is data transported between the first base station andthe terminal apparatus through a Split bearer and an SCG bearer out ofthe MN Terminated bearers.

(Supplementary Note 6)

The communication apparatus according to any one of Supplementary Notes1 to 5, wherein the communication processing section is configured totransmit a signaling message including the data amount information tothe central unit.

(Supplementary Note 7)

The communication apparatus according to Supplementary Note 6, whereinthe communication processing section is configured to transmit thesignaling message via an F1 interface to the central unit.

(Supplementary Note 8)

The communication apparatus according to Supplementary Note 6 or 7,wherein the data amount information includes a Usage count IE.

(Supplementary Note 9)

The communication apparatus according to any one of Supplementary Notes6 to 8, wherein the signaling message is a DATA USAGE REPORT message.

(Supplementary Note 10)

The communication apparatus according to any one of Supplementary Notes6 to 9, wherein the data amount information is information used in amessage transmitted by the central unit to a second base stationoperating, for the terminal apparatus, as a master node of the dualconnectivity.

(Supplementary Note 11)

The communication apparatus according to any one of Supplementary Notes1 to 3, wherein the communication processing section is configured totransmit a user plane frame including the data amount information to thecentral unit.

(Supplementary Note 12)

The communication apparatus according to Supplementary Note 11, wherein:

the data is first data transported between the first base station andthe terminal apparatus through a radio bearer terminated at thesecondary node; and

the data amount information is first data amount information indicativeof an amount of the first data.

(Supplementary Note 13)

The communication apparatus according to Supplementary Note 12, whereinthe communication processing section is configured to transmit a userplane frame including second data amount information to a second basestation operating as a master node of the dual connectivity for theterminal apparatus, the second data amount information being indicativeof an amount of second data transported between the first base stationand the terminal apparatus through a radio bearer terminated at themaster node.

(Supplementary Note 14)

The communication apparatus according to Supplementary Note 13, wherein:

the first data amount information is information that is used in amessage transmitted by the central unit to the second base station; and

the second data amount information is information that is not used inthe message.

(Supplementary Note 15)

The communication apparatus according to any one of Supplementary Notes11 to 14, wherein the user plane frame is a frame of GPRS TunnelingProtocol User Plane (GTP-U).

(Supplementary Note 16)

The communication apparatus according to Supplementary Note 15, whereinthe user plane frame is a DL DATA DELIVERY STATUS frame.

(Supplementary Note 17)

The communication apparatus according to any one of Supplementary Notes1 to 16, wherein the communication processing section is configured totransmit the data amount information in response to an instruction fromthe central unit.

(Supplementary Note 18)

The communication apparatus according to Supplementary Note 17, whereinthe instruction is a Data Usage report Indication Information Element(IE).

(Supplementary Note 19)

The communication apparatus according to Supplementary Note 17 or 18,wherein:

the communication processing section is configured to transmit the dataamount information in response to a signaling message including theinstruction; and

the signaling message is a UE CONTEXT SETUP REQUEST message or a UECONTEXT MODIFICATION REQUEST message.

(Supplementary Note 20)

The communication apparatus according to Supplementary Note 10 or 14,wherein:

the message transmitted by the central unit to the second base stationis a SECONDARY RAT DATA USAGE REPORT message.

(Supplementary Note 21)

The communication apparatus according to any one of Supplementary Notes1 to 20, further comprising a count section configured to count theamount of the data.

(Supplementary Note 22)

The communication apparatus according to Supplementary Note 21, whereinthe count section is configured to count the amount of the data at RadioLink Control (RLC) layer or Medium Access Control (MAC) layer.

(Supplementary Note 23)

The communication apparatus according to any one of Supplementary Notes1 to 22, wherein the communication apparatus is a distributed unitincluded in the first base station.

(Supplementary Note 24)

The communication apparatus according to any one of Supplementary Notes1 to 22, wherein the communication apparatus is the first base station.

(Supplementary Note 25)

The communication apparatus according to any one of Supplementary Notes1 to 22, wherein:

the central unit is a first central unit for a control plane included inthe first base station; and

the communication apparatus is a second central unit for a user planeincluded in the first base station.

(Supplementary Note 26)

The communication apparatus according to any one of Supplementary Notes1 to 25, wherein:

the first base station includes the central unit and a distributed unit;

the central unit is a unit that performs processing of Packet DataConvergence Protocol (PDCP) layer; and

the distributed unit is a unit that performs processing of RLC layer andMAC layer.

(Supplementary Note 27)

The communication apparatus according to any one of Supplementary Notes1 to 26, wherein the dual connectivity is dual connectivity using NR andLong Term Evolution (LTE).

(Supplementary Note 28)

The communication apparatus according to Supplementary Note 27, wherein:

the dual connectivity is E-UTRA-NR Dual Connectivity (EN-DC); and

the first base station is an en-gNB.

(Supplementary Note 29)

A communication apparatus comprising:

a first communication processing section configured to receive dataamount information from a unit included in a first base stationoperating, for a terminal apparatus, as a secondary node of dualconnectivity using at least NR, the data amount information beingindicative of an amount of data transported between the first basestation and the terminal apparatus; and

a second communication processing section configured to transmit amessage for which the data amount information is used to a second basestation operating, for the terminal apparatus, as a master node of thedual connectivity,

wherein the unit is a distributed unit included in the first basestation or a second central unit for a user plane included in the firstbase station.

(Supplementary Note 30)

The communication apparatus according to Supplementary Note 29, wherein:

the unit is the distributed unit; and

the communication apparatus is a central unit included in the first basestation.

(Supplementary Note 31)

The communication apparatus according to Supplementary Note 29, wherein:

the unit is the second central unit; and

the communication apparatus is a first central unit for a control planeincluded in the first base station.

(Supplementary Note 32)

The communication apparatus according to any one of Supplementary Notes29 to 31, wherein the first communication processing section isconfigured to transmit, to the unit, a signaling message including aninstruction to transmit the data amount information.

(Supplementary Note 33)

A terminal apparatus comprising:

a first communication processing section configured to communicate witha first base station operating, for the terminal apparatus, as asecondary node of dual connectivity using at least NR; and

a second communication processing section configured to communicate witha second base station operating, for the terminal apparatus, as a masternode of the dual connectivity,

wherein the first base station includes a unit configured to transmitdata amount information to a central unit included in the first basestation, the data amount information being indicative of an amount ofdata transported between the first base station and the terminalapparatus.

(Supplementary Note 34)

A method comprising:

transmitting data amount information to a central unit included in afirst base station, the data amount information being indicative of anamount of data transported between the first base station and a terminalapparatus, the first base station operating, for the terminal apparatus,as a secondary node of dual connectivity using at least NR.

(Supplementary Note 35)

A program causing a processor to execute:

transmitting data amount information to a central unit included in afirst base station, the data amount information being indicative of anamount of data transported between the first base station and a terminalapparatus, the first base station operating, for the terminal apparatus,as a secondary node of dual connectivity using at least NR.

(Supplementary Note 36)

A computer-readable non-transitory recording medium having recordedthereon a program causing a processor to execute:

transmitting data amount information to a central unit included in afirst base station, the data amount information being indicative of anamount of data transported between the first base station and a terminalapparatus, the first base station operating, for the terminal apparatus,as a secondary node of dual connectivity using at least NR.

(Supplementary Note 37)

A method comprising:

receiving data amount information from a unit included in a first basestation operating, for a terminal apparatus, as a secondary node of dualconnectivity using at least NR, the data amount information beingindicative of an amount of data transported between the first basestation and the terminal apparatus; and

transmitting a message for which the data amount information is used toa second base station operating, for the terminal apparatus, as a masternode of the dual connectivity,

wherein the unit is a distributed unit included in the first basestation or a second central unit for a user plane included in the firstbase station.

(Supplementary Note 38)

A program causing a processor to execute:

receiving data amount information from a unit included in a first basestation operating, for a terminal apparatus, as a secondary node of dualconnectivity using at least NR, the data amount information beingindicative of an amount of data transported between the first basestation and the terminal apparatus; and

transmitting a message for which the data amount information is used toa second base station operating, for the terminal apparatus, as a masternode of the dual connectivity,

wherein the unit is a distributed unit included in the first basestation or a second central unit for a user plane included in the firstbase station.

(Supplementary Note 39)

A computer-readable non-transitory recording medium having recordedthereon a program causing a processor to execute:

receiving data amount information from a unit included in a first basestation operating, for a terminal apparatus, as a secondary node of dualconnectivity using at least NR, the data amount information beingindicative of an amount of data transported between the first basestation and the terminal apparatus; and

transmitting a message for which the data amount information is used toa second base station operating, for the terminal apparatus, as a masternode of the dual connectivity,

wherein the unit is a distributed unit included in the first basestation or a second central unit for a user plane included in the firstbase station.

(Supplementary Note 40)

A method comprising:

communicating with a first base station operating, for a terminalapparatus, as a secondary node of dual connectivity using at least NR;and

communicating with a second base station operating, for the terminalapparatus, as a master node of the dual connectivity,

wherein the first base station includes a unit configured to transmitdata amount information to a central unit included in the first basestation, the data amount information being indicative of an amount ofdata transported between the first base station and the terminalapparatus.

(Supplementary Note 41)

A program causing a processor to execute:

communicating with a first base station operating, for a terminalapparatus, as a secondary node of dual connectivity using at least NR;and

communicating with a second base station operating, for the terminalapparatus, as a master node of the dual connectivity,

wherein the first base station includes a unit configured to transmitdata amount information to a central unit included in the first basestation, the data amount information being indicative of an amount ofdata transported between the first base station and the terminalapparatus.

(Supplementary Note 42)

A computer-readable non-transitory recording medium having recordedthereon a program causing a processor to execute:

communicating with a first base station operating, for a terminalapparatus, as a secondary node of dual connectivity using at least NR;and

communicating with a second base station operating, for the terminalapparatus, as a master node of the dual connectivity,

wherein the first base station includes a unit configured to transmitdata amount information to a central unit included in the first basestation, the data amount information being indicative of an amount ofdata transported between the first base station and the terminalapparatus.

This application claims priority based on Japanese Patent ApplicationNo. 2018-023331 filed on Feb. 13, 2018, the entire disclosure of whichis incorporated herein.

In a mobile communication system, it will be possible to report anamount of data from a secondary node (SN) to a master node (MN) in dualconnectivity.

What is claimed is:
 1. A first unit of a central unit of a first basestation, the first unit comprising a controller and a transceiver,wherein: the central unit is configured to host at least PDCP layer inthe first base station; and is connected to a distributed unit via afirst interface, the distributed unit hosting RLC, MAC and PHY layers inthe first base station; and wherein the controller is configured to hostat least a user plane of the PDCP layer hosted by the central unit; andthe transceiver is configured to transmit, to a second unit via a secondinterface, first information indicative of a volume of data processed bythe first unit, wherein the second unit is configured to host at least acontrol plane of the PDCP layer hosted by the central unit.
 2. The firstunit according to claim 1, wherein the volume of data is an amount ofdata used by a terminal apparatus.
 3. The first unit according to claim1, wherein the first base station is a gNB.
 4. The first unit accordingto claim 1, wherein the first base station is an en-gNB.
 5. The firstunit according to claim 4, wherein the first base station is a secondarynode in E-UTRA-NR Dual Connectivity.
 6. The first unit according toclaim 1, wherein the first base station is connected to an EvolvedPacket Core (EPC).
 7. The first unit according to claim 1, wherein thefirst base station is connected to a 5G core network.
 8. The first unitaccording to claim 1, wherein the first base station is a secondary nodein Dual Connectivity; and the first information is transmitted by thesecond unit to a master node in Dual Connectivity.
 9. A second unit of acentral unit of a first base station, the second unit comprising acontroller and a transceiver, wherein: the central unit is configured tohost at least PDCP layer in the first base station; and is connected toa distributed unit via a first interface, the distributed unit hostingRLC, MAC and PHY layers in the first base station; and wherein thecontroller is configured to host at least a control plane of the PDCPlayer hosted by the central unit; and the transceiver is configured toreceive, from a first unit via a second interface, first informationindicative of a volume of data processed by the first unit, wherein thefirst unit is configured to host at least a user plane of the PDCP layerhosted by the central unit.
 10. The second unit according to claim 9,wherein the volume of data is an amount of data used by a terminalapparatus.
 11. The second unit according to claim 9, wherein the firstbase station is a gNB.
 12. The second unit according to claim 9, whereinthe first base station is an en-gNB.
 13. The second unit according toclaim 12, wherein the first base station is a secondary node inE-UTRA-NR Dual Connectivity.
 14. The second unit according to claim 9,wherein the first base station is connected to an Evolved Packet Core(EPC).
 15. The second unit according to claim 9, wherein the first basestation is connected to a 5G core network.
 16. The second unit accordingto claim 9, wherein the first base station is a secondary node in DualConnectivity; and the transceiver is configured to transmit the firstinformation to a master node in Dual Connectivity.
 17. A methodperformed by a first unit of a central unit of a first base station,wherein at least PDCP layer in the first base station is hosted by thecentral unit; and the central unit is connected to a distributed unitvia a first interface, the distributed unit hosting RLC, MAC and PHYlayers in the first base station, the method comprising: hosting atleast a user plane of the PDCP layer hosted by the central unit; andtransmitting to a second unit via a second interface, first informationindicative of a volume of data processed by the first unit, wherein thesecond unit is configured to host at least a control plane of the PDCPlayer hosted by the central unit.
 18. The method according to claim 17,wherein the volume of data is an amount of data used by a terminalapparatus.
 19. The method according to claim 17, wherein the first basestation is a gNB.
 20. The method according to claim 17, wherein thefirst information is transmitted by the second unit to a master node inDual Connectivity.